Abstract : Awareness and activities in the centres of coordination. In Situated Action models, issued from ethno-methodology, the awareness state present in Coordination Centers constitutes the foundation necessary for coordinating operators- activities, which in turn, will assure a robust work collective. This paper analyses firstly the different acceptations of the word awareness, then what Situated Action models have brought toward furthering the understanding of mutual intelligibility and finally, how the overuse of the activity concept, combined with it-s under-qualification, limits the range of these models. By using a recurring misunderstanding sampled from a study conducted at the Central Control Post of the A line RER Paris subway system, this paper invokes not only the necessity for taking into consideration the operators- specific activities, but also that of enlarging the situation analyzed so as to include social and institutional dimensions : how they-re inscribed in the locality, in the ecology of the Center, in the artifacts, in the definition of tasks, in the operators- places in relation to each other and the direct effects of these dimensions on mutual cooperation and intelligibility.